Every oil and gas well drilled utilizes mechanical apparatus to clean the drilling mud returned from the wellbore of the various drill cuttings, chips and particulates carried up and out of the wellbore as the well is being drilled. Recognized kinds of mechanial mud cleaning equipment has gradually been developed such as shale shakers, desanders, desilters and degassers.
An interesting background for such drilling muds may be found in the paper of J. Kelley, Jr.: "Drilling Fluids Selection, Performance and Quality Control", as published in the May, 1983 issue of the Journal of Petroleum Technology, pgs. 889-898. Also see the Handbook No. 7: "Mud Cleaners and Combination Separators" published by the Gulf Publishing Company, Book Division, Houston, Tex.
The present invention employs a combination of special vibratory screening and hydrocycloning steps which serve to replace the above identified mechanical separation units with a single integrated unit.
The nearest known prior art relating to apparatus utilized for performing the special screening steps above-identified are U.S. Pat. No. 3,900,628 to Stewart, 1955 French Patent No. 1,089,947 to Chauvin, and 1952 Netherlands Patent No. 70,820 to Voor.
The most pertinent prior art known for the apparatus employed for the hydrocycloning steps of the present invention is U.S. Pat. No. 4,019,980 to Beery.